Method of producing pure zinc solution



ED STATES PATENT QFFHCE.

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Be it known that'I, EMA-N iii KA'RDOS, a citizen of Hungary and residentof Newark, in the county of l lssex, and State of New Jersey, have ihventedrerta'in new and' useful Methods of Producing Pure Zinc Solutions, of which the following is a specificatioii'.

The invention relates to a novel process for eliminating impurities, such as salts of other metals, particularly irbn and metals which are electronegative to zinc, that is, which are befow zinc in the electi'omotive series" of the metals, from solution's'of zinc salts, such assulphate of zinc and chloride of zinc resulting from any of the well known processes which produce such sa'lts, including "the" recovery of zinc from galvanized scra or zinc coated iron.

It is a wel known fact use it is di'fiicult to precipitate all iron out of any zinc solution containing the same, especially when it is imperative to remove the last traces of the iron; This is evident from the relative prices of -zi'hc salts containing different proportions of contaminati g iron. For instance, commercial zine sulphate containing 'alroutl037 iron sells for about four cents per pound in normal times, Whereas the chemically pure zinc sulphate containing not more than .001% iron sells for forty cents per pound in the same market. The

, differences in the cost of the twoproducts is represented by the expense of removing all but the mere trace of iron.

Many processes have been suggested and employed for the removal of iron from solutions of zinc salts, and it is the common practice to first oxidize the iron content and then precipitate the same by various reagents. All of these processes, however, are either incomplete, inasmuch as they fail to remove all of the iron, or on the other hand, are too expensive for economical industrial application.

The present invention is designed to obviate both the difiieulties and expensiveness of the prior art methods and to successfully eliminate all of the objectionable iron or metals which are electronegative to zinc from zinc salts in a very simple and inexpensive manner.

In practice I proceed as follows, in case of the removal of iron from zinc salts The crude zinc sulphate or zinc chloride Speciflcationof Letters Patent. Patented Mm, 14, 1998/2.

' Application m r December 20, 1919. Serial mi. 3%,311'.

solution, which may be the product oi a de alvanizing process, or any ofthe other wel known processes which yield one or the other of the salts mentioned, is heated and the iron oxidized by any known commercial process, for instance, by the additionof potassium or sodium chlorate, chlorine or other oxidizing medium, after which galvanized scrap or zinc coated iron is immersed in the solution, with the result that the' acikl liberated during the oxidizing reaction unites with the zinc from the scrap, in accordance with the following reaction:

again for further reactions on other soluticns until the zinc coating thereon has been exhausted, The solution is then carefully filtered, and will, as indicated, be found entirely free from iron. In case any cloudiness remains in the solution, sulphuric acid or hydrochloric acid is added in appropriate amounts until the solution is rendered perfectly clear.

The advantages of this simple and inexpensive process over other known methods are manifold, and some of them may be recited as follows: First, all of the acid combined with the iron in the solution is profitably used to reduce proportionate quantities of zinc sailts, viz: zinc sulphate or zinc chloride, depending upon whether the iron was in the sul hate or chloride form. In other processes it was found necessary to neutralize this acid with lime or the like and remove the resultant roduct as ea cium sul hate or calcium chliiride, which are of litt e value and are ordinarily regarded as waste products. Second, the galvanized scrap after being stri pad of its zmc coating may be used effective y in the steel industry tasted iron oxide, not heih'oointtmihaterl with lime or thelike, is in ltseli a valuable by-product. Fourth, both theapparatus and the procedure necessary tocarry out the:'

process are quite sim lo and inexpensive in the matter of time, la or and materials, and

there are no waste products. It is a well known fact that metallic zinc when added alone to a solution of zinc salts containing iron or the like, under the so I conditions as hereinbefore described, will not precipitate the. iron or other contaminatin% metal, but it is a highly significant fact t at zinc when associated with a suitable metal, such as iron, aster exam le, galvanized iron scrap, is most efiective he ren for this appears to be that thereaction which takes p ace is not a mere chieal one but is apparently an electrochemical reaction, the iron of the galvanized scrap acting in coniunction with the zinc as a gal- I vamc coup e.

What I claim is:

1. The method of purifying zinc salt solutions which comprises precipitating metals which are electronegative to zinc therefrom by reacting upon the solution with zinc in association Wlth a metal electronegative thereto. I j v 2. The method of purityingzinc salt solutions which comprises precipitating metals" which are 'electronegative to zinc therefrom by reacting upon the solution with galvanized iron. I a

3. The method of purifying zincsalt solu tions which comprises precipitating metals which are electronegative to zinc therefrom by boiling the solution and reacting, upon the same with zinc associated with a metal electronegatire thereto.

tfittie tm ethodof un "'tions'which comprises precipitating metals hy'bo g the'solution and rating upon the same with galvzed iron.

The ethod of eli 'nating' salts ofmetals of the iron group from solutions of 4 ing 1* to the solution and reacting upon the solution "with meta lic zinc associated with a metal electronegative thereto.

6. The method of eliminating salts of which aa'e eleotronegative to 'zint therefrom to zinc salts which comprises adding an oxidiz- 5o metals of the iron group from solutions of zinc salts which comprises adding an oxidizing agent to the solution, and reacting upon the so ution with galvanized iron.

. 7, The method of eliminating salts of metals of the iron group from solutions of zinc salts which comprises boiling the solution, adding an oxidizing agent thereto, and reacting upon the solution with galvanized iron. v v 8. The [method of elinating iron from solutions otzino saltswhich comprises treat- ,ing the solution with metallic .zinc in conjunction with" a metal electronegative thereto. Y 9.- ilhe method of eliminating iron from solutions of zinc salts which comprises treating the solution with galvanized iron.

. 10. The method of eliminating iron from solutions of zinc salts which comprises boils ing the solution with galvanized iron.

11. The method of eliminating iron from solutions of zinc salts which coxnprises adding an oxidizing agent, and boiling the solution with galvanized iron.v

Si ned at Chrome, N. J.-, in the county of Mid lesenand State of New Jersey, this 18th day of December, A. l). 1919. 

